US Secretary of State Mike Pompeo today criticised the weekend attacks on the Saudi oil industry as an “act of war” as President Trump ordered a substantial increase in sanctions against Iran, which Washington has linked to the strikes.

The comments raise the risk of a wider conflict in the tinderbox Gulf region after the weekend strikes on the heart of the kingdom's oil industry knocked out half its production.

Mr. Pompeo's comment came as Saudi Arabia displayed what it said were fragments of 25 drones and cruise missiles fired at two facilities in the country's east, leaving them engulfed in flames.

He also said there was no evidence the attacks had been launched from Iraq amid media speculation this was the case.

Yemen's Iran-backed Huthi rebels, who have claimed Saturday's strikes, vowed meanwhile they had the means to hit "dozens of targets" in the United Arab Emirates.